The objectives of this research are to study the epidemiological, clinical, pathological, therapeutic, and pathogenic aspects of meningoencephalitis due to free-living amebas (especially Naegleria and Hartmannella-Acanthamoeba). Cases of PAM will be searched for in the Richmond, Virginia area; CSF samples from patients admitted to the Medical College of Virginia Hospitals will be examined and cultured for such amebas; debilitated and immunosuppressed patients will be studied for oropharyngeal or nasal carrier states; in vitro sensitivity studies of antiamebic agents will be continued; patients with sino-pulmonary diseases will be studied; animal pathogenicity studies involving a variety of free-living amebas will be performed; and amebas will be studied morphologically using electron-microscopy.